Hello guys,
I'm not an expert of 3d printing and also I'haven't a good knowledge of 3d modelling.
As I work as an archaeologist I need to reproduce some small objects like ancient coins to make plastic replicas.

Can you explain to me how to do a 3d .stl model from an image in .jpg or .bmp (in black and white of course) ? Are there some freeware software to make this operation?